midparent

Midparent, in genetics and growth assessment, refers to midparental height (MPH), the average of the biological parents’ heights. It is used as a simple index of a child’s genetic potential for adult height and appears in pediatric growth studies and clinical discussions about growth trajectories. MPH serves as a rough predictor rather than a precise forecast.

Calculation methods vary. The most basic approach uses the arithmetic mean of the two parental heights: MPH = (father’s height + mother’s height) / 2. In some clinical contexts, a sex-adjusted version is employed to better estimate the expected height for a specific child. For example, for a boy, MPH may be calculated as (father’s height + mother’s height + 13 cm) / 2 (or equivalently, add about 5 inches to the sum and then divide by 2); for a girl, MPH may be (father’s height + mother’s height − 13 cm) / 2 (subtract about 5 inches before dividing by 2). These adjustments reflect average differences in adult height between sexes.

Use and limitations. MPH is intended to provide a rough sense of a child’s potential adult height when used with growth charts and velocity data. Height is a polygenic trait influenced by many genes as well as environmental factors such as nutrition, health, and endocrine conditions; as a result, actual adult height can deviate from MPH. Measurement error in parental height and secular trends in height can also affect accuracy. MPH remains a convenient, population-level tool rather than a definitive predictor for any individual.